Minimally invasive surgical (MIS) tools and procedures can often be preferred over traditional open surgical techniques due to their ability to decrease post-operative recovery time and to leave minimal scarring. Laparoscopic surgery is one type of MIS procedure in which one or more small incisions are formed in the abdomen of a patient and a trocar is inserted through each incision to provide a surgical access pathway for an appropriate surgical tool. Trocars can additionally provide an internal seal assembly for maintaining insufflation of the abdomen during a surgical procedure.
A variety of MIS tools can be inserted into the abdominal cavity of a patient via a trocar and maneuvered from outside the abdomen. Laparoscopic surgical tools, for example, are often similar to those used in traditional surgical procedures, with the exception that laparoscopic surgical tools possess an elongate shaft extending from an end effector to a location outside the abdomen. The end effector is the surgically functional part of the surgical tool. The shaft protrudes externally through a trocar when the surgical tool is inserted in the abdomen of a patient, and an external portion of the surgical tool provides a means for manipulating and communicating with the end effector. Once inserted in a patient's body, the end effector can engage and/or treat tissue in a number of ways to achieve a desired diagnostic or therapeutic effect. Illustrative end effectors of laparoscopic and similar surgical tools include, but are not limited to, scissors, graspers, needle drivers, clamps, staplers, cauterizers, suction tools, irrigation tools, clip-appliers, and the like.
Robotic surgery represents a specialized class of laparoscopic surgical procedures. Instead of directly engaging a surgical tool, as in traditional laparoscopic surgery, a surgeon instead manipulates and engages the surgical tool using an electronic interface communicatively coupled to a robotic manipulator. Manipulation and engagement of a surgical tool under robotic control can allow much more precise surgical procedures to be performed in many instances. A surgeon need not necessarily even be in the operating room with the patient. Advantageously, robotic surgical systems can allow intuitive hand movements to be realized by maintaining a natural eye-hand axis. In addition, robotic surgical systems can incorporate a “wrist” at the end effector to provide natural, hand-like articulation during a robotic surgical procedure. The wrist can also facilitate an expanded and more complex range of motion than is possible with a human wrist, which can allow highly elaborate and precise surgical procedures to be performed.
In robotic surgery, one or more arms of a robotic manipulator are mounted to corresponding surgical tools, and the tool(s) is/are manipulated and engaged under the direction of a surgeon during a surgical procedure. Each arm has one or more joints to facilitate manipulation of its attached surgical tool and a mounting fixture to promote the tool's attachment with a complementary housing at the proximal end of the tool. The housing includes one or more mechanisms for actuating the end effector, such as a system for instigating movement of the end effector upon a suitable input from the mounting fixture. For example, the mounting fixture may include one or more drive couplers (e.g., rotary or linear drive couplers) configured to engage a suitable component in the housing and produce a corresponding motion in the end effector (e.g., rotation, pitch, yaw or actuation).
Most conventional laparoscopic surgical tools, including robotic surgical tools, employ multiple elongate members that pass through the elongate shaft within a lumen and establish mechanical communication between the mechanism in the housing and the end effector. Specifically, in many instances, the elongate members deploy or retract in response to a mechanical input from the mounting fixture and housing to convey surgical instructions to the end effector. Illustrative elongate members within laparoscopic and similar surgical tools include, for example, high-durability cables, bands, lines, cords, wires, ropes, strings, twisted strings or like structures that extend continuously from the housing to the end effector. These and similar elongate members are collectively referred to herein as “cables”. Similarly, surgical tools containing such cables may be referred to herein as “cable-driven surgical tools.”
One drawback of laparoscopic and similar cable-driven surgical tools is that their cables are prone to weakening (fatigue) and wear over time, especially where the cables interact with the end effector and are forced into curved shapes (e.g., where contacting internal pulleys). Cable weakening can lead to slackening, which may lessen the end effector's movement precision and possibly compromise the safety and effectiveness of a surgical procedure. Further cable slackening can lead to derailment from the mechanism within the housing or elsewhere. Extreme cable weakening can even lead to catastrophic cable failure (breakage) in some instances. As a result, laparoscopic and similar cable-driven surgical tools are commonly taken out of service well in advance of the time at which cable weakening and wear are anticipated to become problematic.
Once a conventional laparoscopic or similar cable-driven surgical tool is taken out of service due to cable weakening and wear, there is usually no way to recondition the tool effectively without disassembling it nearly completely. In many cases, conventional laparoscopic and similar cable-driven surgical tools may be discarded once taken out of service due to the difficulty of disassembly and refurbishment, despite many of the other tool components remaining within their usable lifetimes.